Partially-acetylated polyvinyl alco-



United States Patent PARTIALLY-ACETYLATED POLYVINYL ALCO- HOL AS ASOIL-'SUSPENDING AGENT Willie Fong, Richmond, and Harold P. Lundgren,Berkeley, Calif., assignors to the United States of America asrepresented by the Secretary of Agricuiture No Drawing. ApplicationDecember 5, 1952, Serial No. 324,424

1 Claim. (Cl. 252161) (Granted under Title 35, U. S. Code (1952), sec.266) A non-exclusive, irrevocable, royalty-free license in the inventionherein described, for all governmental purposes, throughout the world,with the power to grant sublicenses for such purposes, is hereby grantedto the Government of the United States of America.

This invention relates to washing procedures particularly to the washingof textile materials such as fabrics and fibers with aqueous media. Inparticular the invention concerns the use of partially-acetylatedpolyvinyl alcohol in the aqueous washing medium whereby to minimize theredeposition of soil during the washing procedure.

It is well known in the art that a successful washing operation involvestwo separate factors, i. e., (a) the removal of dirt from the textilematerial and (b) keeping the soil suspended in the medium so that itwill not be re-deposited on the textile. In general aqueous washingmedia containing soap fulfill both of these criteria as soap not only isa good soil remover but also keeps the removed soil in suspension sothat little re-deposition takes place. However, the present trend istoward the use of anionic synthetic detergents such as the alkyl benzenesulphonates since these agents can be used in hard Water areas as theirdetersive power is not decreased by the presence of calcium andmagnesium ions. However, these anionic detergents have the disadvantagethat their suspending power is poor. Whereas they are very effectivefrom the standpoint of removing soil they are not so effective inpreventing re-deposition and so cotton fabrics washed with such agentswill be grayer than when using soap. In order to overcome thisdisadvantage, various soil suspending agents are commonly added to theanionic detergents. One of the most commonly used agents is sodiumcarboxymethyl cellulose.

It has now been found that partially-acetylated polyvinyl alcohol hasuseful soil-suspending properties and when added to aqueous washingmedia the degree of soil re-deposition is greatly reduced. It is to beparticularly noted that partially-acetylated polyvinyl alcohol issuperior in this respect to polyvinyl alcohol itself, as illustrated inthe examples herein. Although in its broad aspect this inventioncomprises the use of any partiallyacetylated polyvinyl alcohol, it is tobe understood that not all the included materials possess the samedegree of effectiveness. Thus it has been found that thosepartiallyacetylated polyvinyl alcohols which are acetylated to theextent of from about to about and which have an average molecular weightfrom about 10,000 to about 20,000 exhibit optimum soil-suspendingproperties.

In applying this invention in practice the partiallyacetylated polyvinylalcohol may be dispersed into the aqueous washing medium in aconcentration from about 0.001% to about 0.l%the higher proportionsgiving the greater degree of protection against soil re-deposition. itis obvious that the proportion of the partially-acetylated polyvinylalcohol can be higher than the above range but in general increasing theconcentration above 0.1% gives little if any added protection. Ifdesired, the partiallyacetylated polyvinyl alcohol can be incorporatedwith the detergent so as to form a composition which on dissolving inwater furnishes the desired washing medium. To this end, the detergentis mixed with about 2 to 10% of the aforesaid soil-suspending agent.

in carrying out Washing operations in accordance with this invention,the fabric or other textile material is agitated in the usual mannerpreferably at elevated temperatures as commonly used in laundries withthe aqueous media containing the partially-acetylated polyvinyl alcoholand the detergent. As the detergent one may use any of the materialscommonly used for washing purposes.

The detergent may be, for example, of the anionic or non-ionic types. Inthe first category are included ordinary soaps, that is, sodium orpotassium salts of the higher fatty acids, or usually, mixtures ofhigher fatty acids as are present in naturally occurring oils and fats.Also included in the anionic category are the detergents of thesulphonate or sulphate type. As well known in the art, a multitude ofsuch materials are available, including the alkyl (Cs-C13) sulphates,the alkyl (C8C18) sulphonates, the alkyl (Cs-C18) aromatic sulphonates,the monoor di-alkyl (CG-C18) esters of sulphosuccinic acid, sulphonatedor sulphated amides of the higher fatty acids such as N-sulphoethylstearamide, and so forth. These compounds are generally employed in theform of their salts, i. e., their sodium, potassium, ammonium or aminesalts. Some of the particular detergents which may be used are: sodiumoctyl sulphate, sodium nonyl sulphate, sodium decyl sulphate, sodiumundecyl sulphate, sodium dodecyl sulphate, sodium tridecyl sulphate,sodium tetradecyl sulphate, sodium pentadecyl sulphate, sodium hexadecylsulphate, sodium heptadecyl sulphate, sodium octadecyl sulphate, sodiumoleyl sulphate, sodium octyl sulphonate, sodium nonyl sulphonate, sodiumdecyl sulphonate, sodium uudecyl sulphonate, sodium dodecyl sulphonate,sodium tridecyi suiphonate, sodium tetradecyl sulphonate, sodiumpentadecyl sulphonate, sodium hexadecyl sulphonate, sodium octadecylsulphonate, sodium oleyl sulphonate, sodium salt of di-octylsulphosuccinate, sodium octyl benzene sulphonate, sodium nonyl benzenesulphonate, sodium decyl benzene sulphonate, sodium undecyl benzenesulphonate, sodium dodecyl benzene sulphonate, sodium tridecyl benzenesulphonate, sodium tetradecyl benzene sulphonate, sodium pentadecylbenzene sulphonate, sodium hexadecyl benzene sulphonate, sodiumheptadecyl benzene sulphonate, sodium octadecyl benzene sulphonate,sodium tri (isopropyl) benzene sulphonate, sodium tri (is-obutyl)benzene sulphonate, sodium tri (isopropyl) naphthalene sulphonate,sodium tri (isobutyl) naphthalene sulphonate, and so forth. Thecommercially available detergents are generally not pure compounds butare mixtures of homologous compounds and are quite satisfactory. Thusfor example, the sodium alkyl benzene sulphonate wherein the alkyl groupcontains 12 to 18 carbon atoms is a well known detergent. Others are: amixture of sodium aiiiyi suiphates consisting mostly of sodium laurylsulphate; a mixture of sodium alkyl phenol sulphonates wherein the alkylgroup con tains 12 to 18 carbon atoms; and a mixture of sodium alkylsulphonates wherein the alkyl group contains 10 to 18 carbon atoms. Asnon-anionic detergents one may employ polyalkylene glycol esters, ethersand thioethers of the following types:

wherein the Rs represent long chain alkyl radicals of 8 to 12 carbonatoms and n is an integer from about 4 to 12. Other non-anionicdetergents are the long-chain fatty acid esters of anhydrosorbitol, orthe polyethylene glycol addition products of such esters. It is evidentthat the particular detergent used is not critical except that oneshould be chosen which is generally useful in emulsifying and detergentapplications.

The concentration of the detergent is not critical within a wide rangeand depending on the soil removal efficiency of the particular agent,the range of concentration may be from about 0.05% to about 0.5%. Ifdesired, the soil removal efliciency of the detergent may be increasedby addition to the aqueous medium of any of the usual types of builderssuch as sodium hexametaphosphate, tetra sodium pyrophosphate, sodiumtripolyphosphate, trisodium phosphate, borax, sodium carbonate, sodiumsilicate, sodium metasilicate, and so forth.

The following examples illustrate the invention in greater detail. Theknown soil-suspending agent, sodium carboxymcthyl cellulose, wasemployed in some of the experiments for comparative purposes. In all theexperiments, carbon black was added to the washing media to test thesoil-suspending power of the various materials under test. Obviously inpractice of the invention, no carbon black or other soil would be addedto the washing medium.

Example I A series of experiments were carried out in which cleanswatches of cloth were agitated in an aqueous media containing asynthetic detergent, various soil-suspending agents at variousconcentration levels, and carbon black. The treated swatches were thensubjected to reflectance measurements to measure the amount of soil(carbon black) which had been deposited on the fabric thus to comparethe effectiveness of the soil-suspending agents. The reflectance valuesare an index of the cleanness of the cloth; the higher the proportion oflight reflected the cleaner the cloth. The experiments were carried outas follows:

A standard washing medium was prepared containing: water; sodium alkyl(Ci2C18) benzene sulphonate, 0.12%; sodium tripolypliosphate, 0.08%;sodium car bonate, 0.04%; and carbon black, 0.1%. The pH of thissolution was about 10.3. To samples of the standard medium were addedvarious soil-suspending agents as hereinafter indicated. Each solutionso prepared was tested as follows:

Two hundred cc. of the test solution was placed in a pint jair togetherwini a swatch of a standard bleached muslin (cotton) cloth and 20%stainless-steel balls. The jar was then sealed and placed in aLaunderometer and agitated by rotation at 140 F. for 20 minutes. Thetest swatch was then removed, rinsed 4 times with distilled water andagitated with 200 cc. of distilled water in the Launderometei for 10minutes at 140 F. This washing in distilled water was done to removeloosely adherent carbon black so that the results would relate solely toadsorbed soil. The treated swatch was then dried in air, ironed, and thereflectance measured.

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The materials, and proportions used and the results obtained aretabulated below:

Reflectance (expressed in percent) of the washed cloth samplesPartially- Partially- Concentration of soilacetylated acetylatedsuspending agent, percent polyvinyl polyvinyl Sodium alcohol, 11-14%alcohol, li -14% earboxyacetylation, acetyiation, methyl averagemolecaverage molcecellulose ular weight ular weight Reflectance of theoriginal cloth was 70%. Example II For comparative purposes, the washingprocedures as described in Example I were repeated using thepreviouslymentioned soil-suspending agents and several agents which areoutside the scope of this invention. The washed samples were examined asdescribed above; the results are summarized as follows:

Having thus described our invention we claim:

A process for removing soil from a textile material and minimizing there-deposition of removed soil which comprises washing the material withan aqueous medium containing a synthetic organic detergent from theclass consisting of sulfates and sulfonates and a partiallyacetylatedpolyvinyl alcohol acetylated to the extent from about 10% to about 15%and having an average molecular weight from about 10,000 to about20,000.

References Cited in the file of this patent UNITED STATES PATENTS2,226,075 Rowe Dec. 24, 1940

